[RFI] SO2R and 2nd harmonic

Jim Brown jim at audiosystemsgroup.com
Fri Sep 15 14:05:32 EDT 2017


Frank,

I don't view this as an "either-or" situation. That is, BOTH our own 
transmitters and these external non-linear distortion generators can be 
causing the problem. When both are present, BOTH proper stub design/good 
coax wiring AND finding/defeating the external non-linear distortion 
generator are required.

It's the same old story of "peeling the onion" with multi-element 
problems. You fix one element, allowing you to hear the other underlying 
components that were obscured by the one you fixed.

Using the contesting trailer documented in k9yc.com/7QP.pdf, we had no 
issues with harmonics when set up in the middle of nowhere, but DID have 
issues with external distortion sources when set up within a half mile 
or so of "civilization."

73, Jim K9YC

On 9/14/2017 10:13 AM, donovanf at starpower.net wrote:
> Dave's reply is the only one that correctly addresses the problem
> you described. You described your problem as " rise up floor noise
> level about 60 khz on each side from main harmonic frequency."
>
>
> Many contest stations -- including mine -- experience the exact
> problem you describe, it has a name: "RF Flooding" Its caused
> when a powerful RF signal penetrates a non-linear device that has:
> - AC power or digital signals flowing though it, and
> - is connected to wires that receive the powerful fundamental RF
> signal and re-radiate broadband modulated harmonic RFI.
>



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